This invention relates to apparatus for producing a flowable mass, and more particularly to apparatus for producing a flowable filler containing casting resin.
A device of the mentioned type is described in U.S. Pat. No. 5,833,363. This device is provided with a cylindrically constructed, evacuatable container, the container axis of which is oriented essentially in vertical direction. A shaft extending along the container axis has agitation arms and a distribution plate. A flowable, gas-containing mass, for example a filler-containing casting resin, is guided inside this device under the force of gravity and under agitation from a storage space on the top by way of a thin layer degassing system that removes the gas from the flowable mass into a buffer space provided at the bottom of the container. In this buffer space, the degassed mass that has been homogenized by agitation is temporarily stored under agitation prior to further processing. The flowable mass to be homogenized and degassed that is fed into this device first must be produced in a premixer from prepared starting components. In order to obtain an evenly mixed, flowable mass, a pass-through mixing device that is used together with differential scales is usually required for relatively reactive mixtures, since only this ensures a brief staying time of the mixture. Such a device is relatively complex.
The object of this invention is to provide a device of the initially mentioned type that can be used to produce a flowable mass from given starting components with high mixing quality in a simple manner. Such a device is used primarily for producing and processing a flowable mass just before the mass is poured into molds inside a casting apparatus. The mass is mixed from starting components and may also be effectively degassed inside this device. The starting components, for example, a filler and a resin or hardener, are hereby first processed, the filler preferably by hot air fluidization, the resin or hardener by heating, and are then mixed in a mixing device to form a flowable mass. In a following mixing and degassing device, the flowable mass is homogenized by constant agitation, preferably under a vacuum.
In a device according to the invention, the inlet of a container of this device that holds a flowable mass and contains agitation elements is provided with a pass-through mixer in which the starting components are premixed during a first stage, and the premix produced in this way is then mixed during a second stage with flowable mass from the container. The mass produced in this manner in the pass-through mixer then enters the flowable mass in the container in the form of a free jet from the pass-through mixer. As a result of this and because of the simultaneous agitation of the mass inside the container, an intensive circulation of the mass, i.e., a homogeneous mixing and good pre-degassing of the flowable mass, is achieved in a short amount of time. This good mixing is further improved in a space- and energy-saving manner by the combined effect of the free jet and the agitation elements provided in the container. Since the container is able to hold a large volume of flowable mass, it is sufficient if the latter is metered into the container via the pass-through mixer that is operated practically as a parallel arrangement. The starting materials are hereby weighed in batches, and the batches are fed without differential scales via the pass-through mixer directly into the container. By metering the starting components into the pass-through mixer that operates in a graduated manner, sedimentation of solid particles is largely prevented at the same time.
If the container of the mixing device is provided with an upper partial container for holding the flowable mass, a degassing system may be provided additionally in the container below this partial container in order to degas and further homogenize the flowable mass. This means that the flowable mass not only can be mixed from the starting components in the mixing device, but this mass can be degassed and homogenized and possibly also stored at the same time.